Is there a tool for figuring out the missing characters in Windows product keys?

Betonhaus

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For example, and old computer with a Windows 7 key has two characters worn off, so XXXXX-XXXX?-XXXXX-XXXXX-XXXX?
what would be the easiest way to go through all variations to check what the valid ones would be?
 
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Just use KMSAuto.
you're not wrong, but a veneer of legitimacy can pay dividends in the future. I figured I'd try this as I had similar issues before. This is a $40 computer that may be too old to use anyways, but it was worth a shot.

That being said, I found a "ultimate PID checker" that will accept a file, and used excel to generate all possible combinations. it's currently crunching away at the list, seems each wrong key takes about a second to check and it's increasingly taking longer per key
 
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Search for parts of the key on whatever search engine you use with the sets of five you can read. For example, if it's "ABCDE - FGH?J -KLMNO - PQR?T...", search for ABCDE and KLMNO. Someone has almost certainly posted it on a huge page of every Windows product key starting with 3.1
 
I was able to read them by taking a good picture of them and dicking around with image in a photo editor, assuming they're not 100% missing/obliterated.
 
Whelp. 40 minutes later and i realized that of the characters i did have, one i typed as a B instead of a 8
 
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You can normally just contact Windows Support and they'll issue out a new key
 
Unless this is a machine you're planning on keeping offline, you're better off installing Linux Mint or something. Windows 7 is starting to have incompatibility issues with all kinds of software that no longer supports it at all.
I have an elderly Windows 7 laptop that I mostly keep offline for photo editing and scanning purposes as well as playing some games I have on CD-ROM or DVD-ROM like Midtown Madness 1 & 2 and Microsoft Flight Simulator X (2006).

If I was going to replace it with another old Windows computer for offline use, I'd probably go for an XP computer simply because a lot of the CD/DVD-ROM games I have as well as my ancient copies of Photoshop and Microsoft Office Suite won't even work on Windows 7.
 
You can normally just contact Windows Support and they'll issue out a new key
Technically, you could probably also contact them to see what's the missing character. "Hi I have this license key for Windows 7 X Edition but some characters are illegible, the ones that are a FCKGW-BG5etcetc" and they could probably find it in their database and fill in the blanks.

Or just see that it is a genuine key and give you a new one based on that which would be easier, as long as you have enough proof that you do have a license key and that it is in fact genuine.
 
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Technically, you could probably also contact them to see what's the missing character. "Hi I have this license key for Windows 7 X Edition but some characters are illegible, the ones that are a FCKGW-BG5etcetc" and they could probably find it in their database and fill in the blanks.

Or just see that it is a genuine key and give you a new one based on that which would be easier, as long as you have enough proof that you do have a license key and that it is in fact genuine.
I tried that a year or two ago, and they said that they no longer support windows 7 and refused to help.
 
Unless this is a machine you're planning on keeping offline, you're better off installing Linux Mint or something. Windows 7 is starting to have incompatibility issues with all kinds of software that no longer supports it at all.
To be fair, I'm going to immediately free upgrade to Windows 10. I'm not sure if I can just enter the key into windows 10 or if I have to install 7 then upgrade first.

After that the key will be associated with the hardware and reinstalls will activate automatically.
 
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After chewing away at the list for an hour it spat out one (1) valid Windows 7 key, which the Windows 10 installer accepted.
 
...This process works, but it can get slow very quickly. Each unknown character multiplies the processing time by 36 (A-Z+0-9). One character would've taken under two minutes, two characters took 63 minutes, and three would've taken 38 hours. Plus there's a memory leak or something so the time per key gets longer the further down the list you are. And that's with it using all six cores on my system.
 
This is way outside the scope of OP's question but if anyone is looking for a fun hacking challenge, the real autist's solution for this particular problem is to write a bruteforcer that hooks pidgen.dll / pidgenx.dll and blasts through all the valid combination of characters until the pidgen DLL says "yep, this looks valid." pidgen.dll functions are called during Windows or Office setup when you get the "please enter your license key" prompt and is responsible for validating that what you entered is cryptographically correct. Valid characters in a Microsoft key are 2346789BCDFGHJKMPQRTVWXY. This probably becomes less and less feasible the more characters are missing but for the one or two OP was missing, it shouldn't take long at all to get a valid check.

This may very well be what that "ultimate PID checker" tool is doing too but at least you'll have the knowledge you solved a problem yourself and that your tool isn't harvesting keys to sell in bootleg Aliexpress copies of Windows.
 
This is way outside the scope of OP's question but if anyone is looking for a fun hacking challenge, the real autist's solution for this particular problem is to write a bruteforcer that hooks pidgen.dll / pidgenx.dll and blasts through all the valid combination of characters until the pidgen DLL says "yep, this looks valid." pidgen.dll functions are called during Windows or Office setup when you get the "please enter your license key" prompt and is responsible for validating that what you entered is cryptographically correct. Valid characters in a Microsoft key are 2346789BCDFGHJKMPQRTVWXY. This probably becomes less and less feasible the more characters are missing but for the one or two OP was missing, it shouldn't take long at all to get a valid check.

This may very well be what that "ultimate PID checker" tool is doing too but at least you'll have the knowledge you solved a problem yourself and that your tool isn't harvesting keys to sell in bootleg Aliexpress copies of Windows.
I see that omits characters that can be confused for each other like I and 1 or 5 and S which would reduce checking time, but I'd imagine that checking all possible permutations where only two characters are variable would still take my computer over 30 minutes, so checking all possibilities would take 3.3x10^29 years on my pretty decent gaming system. You'd need a server farm to brute force this in a reasonable timeframe.

My solution only works well if you're missing only two letters and have very good guesses for the rest, as otherwise even brute forcing three letters will take over a week of crunching numbers.

...which I suppose explains why there isn't a tool to figure out missing letters already
 
I see that omits characters that can be confused for each other like I and 1 or 5 and S which would reduce checking time, but I'd imagine that checking all possible permutations where only two characters are variable would still take my computer over 30 minutes, so checking all possibilities would take 3.3x10^29 years on my pretty decent gaming system. You'd need a server farm to brute force this in a reasonable timeframe.

My solution only works well if you're missing only two letters and have very good guesses for the rest, as otherwise even brute forcing three letters will take over a week of crunching numbers.

...which I suppose explains why there isn't a tool to figure out missing letters already
Because in effect, what you're doing is no different than bruteforcing password hashes with John the Ripper or hashcat. Microsoft keys are nothing more than an encrypted string that get decrypted with a specific key / algo in pidgen.dll (and in Microsoft's activation servers), as I understand it.
 
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